The synthesis of some imidazo[1,2-a]pyridine derivatives is described in Recl. Trav. Chim. Pays-Bas 1949, 68, 441-470, in J. Org. Chem. 1954, 19, 1370-1374, in J. Heterocyclic Chem. 1988, 25, 129-137, in International patent application WO 00/08021 or in J. Org. Chem. 2000, 65, 9201-9205. According to J. Prakt. Chem. 1971, 313, 977-985, imidazo[1,2,-a]pyridines bearing a benzothienyl, thienyl or benzofuranyl group have been prepared by condensation of α-haloketones or α-hydroxyketones with amidines. The synthesis and antimicrobial action of furyl derivatives of imidazo[1,2-a]pyrimidine is reported in Khim.-Farm. Zh. 1970, 4, 20-26.
Different uses have been described for imidazo[1,2-a]pyridine derivatives. The preparation of 2-[p-(dimethylamino)phenyl]-imidazo[1,2-a]pyridine as an azo dye and its evaluation as disperse dye on synthetic fibers, cellulose acetate, and cotton is described in Boll. Sci. Fac. Chim. Ind. Bologna 1966, 24, 205-214. Fluorescent properties of imidazo[1,2-a]-pyridine-based compounds are described in Bull. Chem. Soc. Jpn. 1999, 72(6), 1327-1334. Japanese patent applications JP 50-140477, JP 51-004194 and JP 51-125095 report the analgesic, antiinflammatory, antipyretic, and local anesthetic activities of certain phenyl-imidazo[1,2-a]pyridines wherein the phenyl ring is substituted by —CR1R2COOH, —CR1R2COOR, —CR1R2CONH2, —CR1R2CSNH2, —CR1R2CN, —CO2—(CH2)1-4—NR3R4 or —CH2OH and R, R1, R2, R3, and R4 are hydrogen or alkyl. According to Arzneim.-Forsch. 1981, 31(7), 1111-1118, the most preferred compound thereof, viz. 4-imidazo[1,2-a]pyridin-2-yl-α-methyl-benzeneacetic acid (miroprofen) is effective in suppressing pain responses and acute inflammation accompanied by increased vascular permeability. The use of imidazo[1,2-a]pyridines substituted at the 2 and 6 positions as anthelmintic and fungicidal agents is disclosed in U.S. Pat. No. 3,701,780. Isothiocyanato derivatives like 2-(4-isothiocyanato-phenyl)-6-methyl-imidazo[1,2-a]pyridine are described as antihelmintics in Swiss patent No. CH 590 862.
The use of imidazo[1,2-a]pyridine derivatives as inhibitors for STAT6 6 transcription factor activation and IL 4 antagonists for treatment of allergic, autoimmune, parasital, viral, and bacterial diseases, tumors, host-vs. graft syndrome, systemic lupus erythematosus, and AIDS is disclosed in Japanese patent application No. JP 11-116481.
According to Eur. J. Med. Chem. 1994, 29(5), 339-342, aryl- or pyridyl-substituted fused imidazoles such as 2-(4-pyridinyl)-imidazo[1,2-a]pyridine, possess cardiotonic activity. N-(4-imidazo[1,2-a]pyridin-2-yl-phenyl)-methanesulfonamide has been prepared and is reported as an antithrombotic and cardiovascular agent in European patent application EP 0 185 345. According to Eur. J. Med. Chem. 1987, 22(5), 457-462, certain imidazo[1,2-a]pyrimidines, e.g. 2-(2-furanyl)-imidazo[1,2-a]pyridine, were tested for bronchodilator activity and for inhibition of a cardiac phosphodiesterase. Phosphonic acid derivatives of imidazo[1,2-a]pyridines, e.g. [5-(6-chloroimidazo[1,2-a]pyridin-2-yl)-2-furanyl]-phosphonic acid, are described as human liver fructose-1,6-bisphosphatase inhibitors in International patent application WO 98/39342.
N,N,6-trimethyl-2-(4-methylphenyl)-imidazo[1,2-a]pyridine-3-acetamide (Zolpidem) and its use as anticonvulsant and hypnotic was first disclosed in European patent application EP 0 050 563. Further imidazo[1,2-a]pyridine derivatives with anticonvulsant, hypnotic and anxiolytic activity are also described in the patent applications EP 0 092 458, EP 0 092 459, EP 0 172 096, FR 25 81 646, EP 0 234 970, EP 0 251 859 and EP 0 267 111. Eur. J. Pharmacol. 1986, 130(3), 257-263, reports that Zolpidem possesses agonist properties at central benzodiazepine receptors and according to Br. J. Pharmacol. 2000, 131(7), 1251-1254 the mechanism of action of Zolpidem in vivo is based on its high affinity to the α1-GABAA receptor benzodiazepine site.